The correct answer is probably mammary glands, given that you provided very little context. It is a proven fact that almost every female mammal has mammary glands — and out of the other choices, most organisms do not have lungs, large brains, or placentas.
your answer would be B, because population density means people per square mile
The answer is P-site. Ribosomes are composed of two subunits, one
small and one large. Four binding sites are located on the ribosome, one for
mRNA and three for tRNA. The three tRNA sites are labeled P, A, and E. The A
site (acceptor site), binds to the aminoacyl tRNA, which holds the new amino
acid to be added to the polypeptide chain.
